One-way clutch

ABSTRACT

A one-way overrunning clutch or freewheel provided with clamping-components, known as sprags, cams and the like, made of ceramic material, such as a high alumina ceramic.

v Unlted States Patent 1 1 1 3,730,316 Zimmer 1 May 1, 1973 ONE-WAY CLUTCH 3,563,621 2 1971 Gruss .f. ..30s 23s 1 3,428,374 2/1969 Orkin et a1 ..308/238 X [75 Inventor George 3,022,685 2/1962 Annacost ..308/D1G. s [73] Assignee: Borg-Warner Corporation, Chicago, 3,535,007 10/1970 Klingler ..308/241 111. 2,745,437 5/1956 Comstock 138/64 Filed: p 1971 3,284,144 11/1966 Moore et a1. ..308/3 [21] Appl. No.: 139,073 Primary Examiner-A11an D. Hermann Attorney-Donald W. Banner, William S. McCurry 52 US. 01. ..192 41 A, 192/45. 1, 192/107 M and Butcher [51] Int. Cl. ..Fl6d 41/07, F16d 13/60 58 Field of Search ..192/41 A, 45.1, 107 M; [57] ABSTRACT I 308/238 8 A one-way overrunning clutch or freewheel provided with clamping-components, known as sprags, cams [56] References cued and the like, made of ceramic material, such as a high UNITED STATES PATENTS alumina ceramic- 1,694,377 12/1928 Lavaud 192/41 A 8 Claims, 3 Drawing Figures Patented May 1, 1973 mvem'roq 650M615 A Z/MMER BY M 4 4%,?

ONE-WAY CLUTCH SUMMARY OF THE INVENTION been improved by providing ceramic clamping-components, such as sprags, cams and the like, hereinafter referred to as clamping-components. In order to provide sufficient wear resistance and compressive strength, the presently known one-way clutches typically utilize specially hardened clamping-components. For long wear life a hard surface finish is desired which is provided by nitriding or hard chrome plating of the clamping components. These methods of hardening will form a brittle layer or skin which may crack or spall off. In practice lower hardness through-hardened materials are used such as alloy tool steel and 52100 ball bearing steel. These materials have sufficient hardness to withstand the high normal working stress and therefore eliminate the brittle layer.

Long wear life also requires that the profile of the clamping-component be geometrically correct without surface distortions which would cause excessive localized stresses due to uneven bearing surfaces. Alloy tool steel and 52100 ball bearing steel cannot match the strength and stiffness of a properly selected ceramic and so are not as resistant to distortion.

Some of the highly desirable objectives of this invention are to provide a one-way over-running clutch with ceramic clamping-components whereby these components can be provided with high hardness for wear resistance with no brittle layer, and with a high compressive strength and high modulus of elasticity for increased load-carrying capacity. Further, the provision of ceramic clamping-components in a one-way clutch will provide a clutch which will have a higher maximum permissible operating speed since the heat generated will not affect the hardness of the ceramic as greatly as that of steel. Also, by virtue of the exceptional stiffness and dimensional stability of the ceramic clamping-component in a oneway clutch, the clutch will be possessed of increased accuracy and can be used for indexing applications and the like in which one-way clutches provided with steel clamping components would be inappropriate.

Other advantages and novel aspects of the invention will become appartent upon consideration of the following detailed'description in conjunction with the following drawings wherein:

FIG. 1 is a partial sectional view taken through the axis of one form of a one-way clutch showing the ceramic clamping-components in conjunction therewith; and

FIGS. 2 and 3 are views similar to FIG. 1 showing different forms of one-way clutches.

In FIG. 1 a resilient clamping-components cage 10 is shown having clamping-components receiving apertures 11 and is utilized to position clamping-components 12 between the inner and outer races 13 and 14, respectively, whereby the clamping components will be active to provide a driving force between the inner race 13 and the outer race 14 during one direction of relative rotation therebetween, and to provide an overrunning connection between the inner and outer races 13 and 14 during the opposite relative rotation therebetween.

In FIGS. 2 and 3 clamping-components 12A and 12B, respectively, are held in position due to their close proximity and spiral-type garter-springs 15 are utilized to force the clamping-components into position whereby the clamping components will perform as described above between the inner races 13 and outer races 14.

The clamping-components 12, or 12A, or 12B, as the case may be, of this invention are composed of ceramic material. It has been discovered that an alumina ceramic provides the desirable objects of this invention. In

particular, it has been found that the objects of this invention are provided when the clamping-components are composed of an alumina ceramic with a high A1 0 content, as for example, about percent and more A1 0 and preferably of substantially pure A1 0 As an example, on having 99.98 percent A1 0 with a specific gravity of 3.96 has proved very satisfactory.

It is to be understood that the invention is not to be limited to the specific construction and arrangements shown and described, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

I claim 1. In a one-way overrunning type clutch comprising the combination of an inner race member, an outer race member, and means for operatively retaining clamping-components between said outer and said inner race to provide a drive connection therebetween in one direction and an overrunning connection in the opposite direction, the improvement in which said clamping-components are ceramic.

2. A one-way overrunning clutch as defined in claim 1 wherein said ceramic is an alumina ceramic.

3. A one-way overrunning clutch as defined in claim 2 wherein said alumina ceramic is A1 0 4. A one-way overrunning clutch as defined in claim 2 wherein said alumina ceramic is 99.98 percentpure Al O 5. A ceramic clamping component for a one-way overrunning clutch retained between an inner and an outer race to provide a driving connection therebetween in one direction and an overrunning connection in the opposite direction.

6. A clamping-component as recited in claim 5 wherein said ceramic is an alumina ceramic.

7. A clamping-component as recited in claim 6 wherein said alumina ceramic is A1 0 8. A clamping-component as recited in claim 6 wherein said alumina ceramic is 99.98 percent pure A1 0 

2. A one-way overrunning clutch as defined in claim 1 wherein said ceramic is an alumina ceramic.
 3. A one-way overrunning clutch as defined in claim 2 wherein said alumina ceramic is Al2O3.
 4. A one-way overrunning clutch as defined in claim 2 wherein said alumina ceramic is 99.98 percent pure Al2O3.
 5. A ceramic clamping component for a one-way overrunning clutch retained between an inner and an outer race to provide a driving connection therebetween in one direction and an overrunning connection in the opposite direction.
 6. A clamping-component as recited in claim 5 wherein said ceramic is an alumina ceramic.
 7. A clamping-component as recited in claim 6 wherein said alumina ceramic is Al2O3.
 8. A clamping-component as recited in claim 6 wherein said alumina ceramic is 99.98 percent pure Al2O3. 